Cellulose, Starch, Reducing and Non-reducing sugars

Question 1

Starch:

Answer 1

Made out of alpha glucose monosaccharides, and is a coiled, condensed, polysaccharide.
It has glycosidic bonds.

Question 2

Why is it coiled?

Answer 2

The coils allow for larger quantities of starch to be stored.

Question 3

Starch, aka…..?

Answer 3

Starch coil

Question 4

Cellulose:

Answer 4

Made out of beta glucose monosaccharides, and every other monosaccharide is rotated 180 degrees to form a straight line.

Question 5

Cellulose, aka……?

Answer 5

Beta pleated sheet

Question 6

Which disaccharides are reducing sugars?

Answer 6

Maltose and Lactose

Question 7

What is a reducing sugar?

Answer 7

Donates electrons which are used to reduce Cu2+ (blue) to Cu+ (red).
>=>0>=>0
(0 = electron)

Question 8

What test can you use to find a reducing sugar?

Give a description.

Answer 8

Benedicts reagent test.
When you heat benedicts reagant with a reducing sugar the Cu2+ will change to Cu+. Copper Oxide is formed, and a red precipitate.

Question 9

Which disaccharides are non-reducing sugars?

Answer 9

Sucrose.

Question 10

What is a non-reducing sugar?

Answer 10

It is a sugar with no free electrons.
>=>0<=<
(0 = electron)

Question 11

What test can you use to find a non-reducing sugar?

Give a description.

Answer 11

Test with benedicts reagent - no precipitate formed.
Apply dilute hydrochloric acid to a new sample to separate the molecules.
Then neutralise the solution with NaHCO3.
Retest solution with benedicts reagent, a red precipitate will form.